@marceltrapman
when you change the BAUD rate setting in the source/config file to something lower/other you can also use 3.3V Arduinos as (Serial)Gateway. Of cause your controller needs also to be told about the lower BAUD rate.
Check out http://wormfood.net/avrbaudcalc.php?postbitrate=9600&postclock=8 for an overview of Clockspeeds (usually 8MHz for 3.3V and 16MHz for 5V types) and coresponding BAUD rates.
I modified MyConfig.h file and RFM69 driver to allow you build gateway (ethernet or MQTT) with W5100 ethernet and RFM69 radio modules using SoftSPI bus. You can find it at: https://github.com/gieemek/RFM69_softSPI-for-MySensors-2.1.1
@tbowmo more out of curiosity, and from someone that just got started on electronics, so please sorry if this sounds like very noob, but, would it not be safer to plug the V_TARGET LED to the +3.3v pin? How do you ensure that the resistor on the V_TARGET will have constant voltage and that will not blow from over voltage if the VCCio pin is depended on the the Motherboard power?
Thank You and nice work